StrayBassist
Well-known member
Well, here we are.
Unfortunately I don't have a VCDS scanner nor can I afford one; though I am looking into VCDS Lite, though there's conflicting information on what cables will work for it and what cables work on Windows 10..
I had 3 instances where I would suddenly be rev limited to about 3K, and low on power, but no MIL. Turning off the car, waiting a minute or so and turning it back on would fix the issue. I only experienced them after driving the car hard - such as merging onto the highway and really revving the engine out. After this, it didn't happen for a long time until my girlfriend started borrowing my car to commute to work while we repair hers, this time finally tripping the P1550 code, rev limiting the car as well as being very low on power, and getting abysmal fuel economy. (I usually go about 65-75 miles before one 'dot' on the NB fuel gauge goes down, now she's gone through a quarter tank in about 70 miles)
She cleared the code to see if it'd come back, and it did - only once - but the limp mode is persistent now.
So far I've inspected the air filter (I replaced it only 6k miles ago so as expected, it's fine.) and the snow screen seems to already have been deleted by the previous owner, so that's fine.
I didn't notice an abnormal amount of buildup in the intake.
I haven't done a proper vacuum test on all of the lines (if anyone knows where I could get a pump to check them, maybe harbor freight?) but visual and tactile inspection seems that the ones I can get to so far are fine.
I was told to try swapping the N75 valve and N18 solenoids, and I did. The car seemed incredibly sluggish, the turbo was far quieter, and although it was quite a struggle to get up to/above 3K in any gear other than 1st and 2nd, I didn't seem to be rev limited. People have told me to try swapping these two, but not what to actually look for - does this confirm a bad N75 solenoid or not..?
The only thing I haven't really inspected yet is the VNT actuator/vanes, though I plan to when I wake up tomorrow morning and will update accordingly. I kind of doubted it'd be a soot buildup issue since I'd driven the car hard a few times before, taking it to a mountain road, and passing or merging on the highway without issue.
Am I just best off buying the KermaTDI Limp Mode kit and replacing everything, or is it most likely my N75? What can I do to further narrow it down?
EDIT: I just recalled an important detail I'd forgotten about it until checking my text history with the girlfriend; the first time the MIL showed up it also apparently threw a code P1161 (Intake Air Temp Sensor open/short to positive) and P1156 (MAP sensor open/short to ground). I hadn't considered it because those codes only came up once, and because of how many people have told me it's unlikely to be the MAF, but that might be worth investigation.. is MAF cleaner safe to use on our cars?
Unfortunately I don't have a VCDS scanner nor can I afford one; though I am looking into VCDS Lite, though there's conflicting information on what cables will work for it and what cables work on Windows 10..
I had 3 instances where I would suddenly be rev limited to about 3K, and low on power, but no MIL. Turning off the car, waiting a minute or so and turning it back on would fix the issue. I only experienced them after driving the car hard - such as merging onto the highway and really revving the engine out. After this, it didn't happen for a long time until my girlfriend started borrowing my car to commute to work while we repair hers, this time finally tripping the P1550 code, rev limiting the car as well as being very low on power, and getting abysmal fuel economy. (I usually go about 65-75 miles before one 'dot' on the NB fuel gauge goes down, now she's gone through a quarter tank in about 70 miles)
She cleared the code to see if it'd come back, and it did - only once - but the limp mode is persistent now.
So far I've inspected the air filter (I replaced it only 6k miles ago so as expected, it's fine.) and the snow screen seems to already have been deleted by the previous owner, so that's fine.
I didn't notice an abnormal amount of buildup in the intake.
I haven't done a proper vacuum test on all of the lines (if anyone knows where I could get a pump to check them, maybe harbor freight?) but visual and tactile inspection seems that the ones I can get to so far are fine.
I was told to try swapping the N75 valve and N18 solenoids, and I did. The car seemed incredibly sluggish, the turbo was far quieter, and although it was quite a struggle to get up to/above 3K in any gear other than 1st and 2nd, I didn't seem to be rev limited. People have told me to try swapping these two, but not what to actually look for - does this confirm a bad N75 solenoid or not..?
The only thing I haven't really inspected yet is the VNT actuator/vanes, though I plan to when I wake up tomorrow morning and will update accordingly. I kind of doubted it'd be a soot buildup issue since I'd driven the car hard a few times before, taking it to a mountain road, and passing or merging on the highway without issue.
Am I just best off buying the KermaTDI Limp Mode kit and replacing everything, or is it most likely my N75? What can I do to further narrow it down?
EDIT: I just recalled an important detail I'd forgotten about it until checking my text history with the girlfriend; the first time the MIL showed up it also apparently threw a code P1161 (Intake Air Temp Sensor open/short to positive) and P1156 (MAP sensor open/short to ground). I hadn't considered it because those codes only came up once, and because of how many people have told me it's unlikely to be the MAF, but that might be worth investigation.. is MAF cleaner safe to use on our cars?
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.. or at least very good chance.